A grinding machine has a measuring apparatus. Such an apparatus measures the outer diameter of a columnar portion of a workpiece, thereby monitoring the state of grinding of the columnar portion performed by the grinding machine.
As one such type of measuring apparatus for a grinding machine, the configuration disclosed, for example, in Patent Document 1 has been proposed. This grinding machine will now be described with reference to FIGS. 24 and 25. A rotary shaft 103 of a motor (not shown) is supported on the upper surface of a grinding base 101, which can be reciprocated, via a pillow block 102. A grindstone 104 is coupled to the distal end of the rotary shaft 103.
A measuring apparatus 111 is attached to the pillow block 102 to measure the outer diameter of a crankpin 106a of a crankshaft 106. The measuring apparatus 111 is configured as follows. That is, a first tilt arm 114 is supported on the upper surface of the pillow block 102 via a bracket 112, and a support shaft 113, so as to be vertically tiltable. A second tilt arm 116 is coupled to the distal end of the first tilt arm 114 via a coupler shaft 115, so as to be vertically tiltable.
A tubular case 117 is supported at the distal end of the second tilt arm 116, and an operation rod 118 is movably received in the tubular case 117. A pin of a measuring device 119 is attached to the distal end of the operation rod 118. The pin of the measuring device 119 contacts the outer circumferential surface of the crankpin 106a of the crankshaft 106 to measure the outer diameter of the crankpin 106a. A support block 120 is attached to the tubular case 117. A gauge 121 is attached to the support block 120. The gauge 121 is formed to engage with the outer circumferential surface of the crankpin 106a. A guide member 122 is attached to the support block 120. The guide member 122 guides the gauge 121 toward the crankpin 106a. The measuring device 119 is hooked to the crankpin 106a by means of the weight of the first tilt arm 114 and other members.
A cylinder 123 for tilting the first tilt arm 114 is attached to the bracket 112. A weight 125 is coupled to the first tilt arm 114 to maintain the weight balance as shown in FIG. 24. When a piston rod 124 of the cylinder 123 is moved rightward as viewed in FIG. 24, so as to push the weight 125, the first tilt arm 114, the second tilt arm 116, the support block 120, and the gauge 121 are moved from a measurement position shown in FIG. 24 to a home position shown in FIG. 25.